Course of the Facial Nerve in Congenital Ear Deformities

Aberrant pathways of the facial nerve through the temporal bone are related to the severity and type of congenital ear deformity. A facial nerve crossing the middle ear cavity with no bone covering cannot be shown by radiologic techniques but may be inferred from: (1) abnormalities of the first part of the facial nerve canal in the region of the geniculate ganglion, (2) absence of the Fallopian canal, (3) absence of the oval window, (4) absence of the pyramidal eminence, and (5) an exit foramen through the floor of the middle ear. Demonstration of these features is discussed with tomographic and histologic correlation in 2 cases, tomographic and surgical correlation in 31.